Our model for preterm delivery builds on the biologic model proposed by Lockwood and the social model proposed by James by linking social and biomedical risk factors to the three proximate biologic "triggers" (infection, bleeding, stress) of the preterm delivery process. There has been little success in modifying these proximate triggers. Infection could be considered an exception as rates of preterm delivery are lower among women who are diagnosed and treated. But infection screening is not routine and women with late or no prenatal care cannot be screened and treated. Successful prevention of preterm delivery requires knowledge of the more distal determinants, social and biomedical, which influence the triggers of this final biologic pathway. Our model, therefore, focuses on social (socioeconomic status, stress, stress modifiers, racism) factors and how they are mediated by biomedical factors (health behaviors with a focus on douching, physical activity; medical and pregnancy history; acute complications of pregnancy) and the proximate biologic triggers to influence preterm delivery risk. In the proposed study, we will build on recent research, both biological and epidemiological, to identify the factors which affect the risk as well as describe the processes that underlie these relationships. We also go further and consider the context of individual risk factors. Several investigators have demonstrated the influence of neighborhood and work environments on health behaviors and health outcomes of individuals and even on low birth weight. Therefore, to examine contextual physical and economic factors at the neighborhood-level, we will link geocoded addresses of the sample women with existing databases of environmental characteristics for residential neighborhoods in Baltimore City. The design for the study is a cohort with subjects identified prospectively during gestation. Prenatal and postpartum interviews will be conducted to collect data on many of the social and biomedical factors. Medical records will also be reviewed. Biologic specimens will be collected to: (a) assess stress as a biologic construct by measuring cortisol and catecholamine levels, and (b) detect bacterial vaginosis, an infection not routinely screened for and therefore not available in medical records.